docs: def save_related(self, request, form, *args, **kwargs):
          """
          Send the signal `publishing_post_save_related` when a draft copy is
          saved and all its relationships have also been created.
          """
          result = super(PublishingAdmin, self) \
              .save_related(request, form, *args, **kwargs)
          # Send signal that draft has been saved and all relationships created
          if form.instance:
              publishing_signals.publishing_post_save_related.send(
                  sender=type(self), instance=form.instance)
          return result